1. Field of the Invention
The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a page printer and the like, and more particularly it relates to an electrophotographic image forming apparatus having an improved process cartridge portion.
2. Related Background Art
In conventional electrophotographic image forming apparatuses using electrophotographic image forming process, a process cartridge, in which an electrophotographic photosensitive member and process means acting on the electrophotographic photosensitive member are integrally assembled as a cartridge unit, which can detachably mounted to a main body of an image forming apparatus, has been used. By using such a process cartridge, since the user himself can perform the maintenance of the apparatus without the help of any expert, operability is greatly improved. Thus, the process cartridge has widely been used in electrophotographic image forming apparatuses.
In an electrophotographic image forming apparatus using the process cartridge, since the user himself must exchange the process cartridges, a means must be provided for informing the user of the exchanging time for the process cartridge. To this end, in the past, a remaining amount of toner in the process cartridge was detected in the following manners to inform the user of the exchanging time for the process cartridge.
(1) A conductive antenna is disposed in the vicinity of a developing sleeve, and a remaining amount of toner is judged on the basis of the electrostatic capacity between the antenna and the sleeve (i.e., the dielectric constant of toner is utilized).
(2) A laser light emitting element and a light receiving element are provided, and a remaining amount of toner is judged on the basis of the fact that the light emitted from the light emitting element is not received by the light receiving element if there is any toner between these elements (i.e., the light shielding ability of toner is utilized).
(3) A remaining amount of toner is judged on the basis of a weight of a toner container (i.e., the weight of toner is utilized).
(4) The number of copies from the initiation of copying is stored by using a re-writable memory means. Or,
(5) The total light emitting time of a laser is stored by using a re-writable memory means.
A first object of the present invention is to provide a process cartridge and an electrophotographic image forming apparatus to which such a process cartridge can be mounted, which can further improve the above-mentioned conventional techniques and which can always detect a remaining amount of toner correctly to inform the user of the present printable number of sheets.
A second object of the present invention is to provide a process cartridge and an electrophotographic image forming apparatus to which such a process cartridge can be mounted, which can always detect the remaining amount of toner correctly regardless of the kind of a process cartridge to be used.
A third object of the present invention is to provide a process cartridge and an electrophotographic image forming apparatus to which such a process cartridge can be mounted, which can always detect the remaining amount of toner more correctly to inform the user of the remaining usable days of toner.
A fourth object of the present invention is to provide an electrophotographic image forming apparatus which can always detect a remained amount of toner more correctly by using a plurality of detection means for detecting the remaining amount of toner.